Method and device for preventing unpermitted approach of airplanes to objects on the ground which are to be protected

ABSTRACT

The invention concerns a method for preventing airplanes from impermissibly approaching defendable ground objects, the method suggests that a defendable ground object is assigned a virtual prohibited zone spatially surrounding it, with the outer boundary of such zone being provided with a sufficient horizontal minimum distance from the ground object and a vertical minimum distance determining a given minimum crossing altitude, that the prohibited zone is assigned a virtual correction zone laterally surrounding it whose outer boundary has a horizontal minimum distance from the outer boundary of the prohibited zone in any case sufficient for any forced deviation corrections and an altitude equal to that of the prohibited zone; that the correction zone is assigned a virtual alarm zone spatially surrounding it whose outer boundary has a horizontal minimum distance from the outer boundary of the correction zone in any case sufficient for manual deviation corrections; that the geographical data of the outer boundaries of at least the alarm and the correction zone are recorded and digitally stored together with the vertical minimum distance or the minimum crossing altitude and stored with access protection provided in every airplane and displayed in the cockpit.

The invention relates to a method for preventing airplanes fromimpermissibly approaching defendable ground objects, with the momentaryflight position being recorded in a satellite-based way and used for thepurposes of performing manual and automatic flight corrections.Furthermore, the invention relates to a facility for applying suchmethod by means of a satellite-based navigational system receiver, acomputer equipped with a memory, an autopilot system for airplanes, ananticollision system for airplanes, an altimeter provided with a displayas well as signaling means in the cockpit of the airplane.

In view of the continuously rising danger of terrorist attacks there isa growing need to protect highly important and endangered ground objectssuch as nuclear power stations and industrial facilities againstcolliding airplanes. Certainly, many safety provisions exist in order toprevent such collisions even under unfavorable conditions. However, thisrequires the crew to strictly adhere to such safety provisions, which isnot the case in the event of terrorist targets.

The present invention is therefore based on the task of creating amethod and a facility allowing defendable ground objects to be reliablyprotected from being impermissibly approached by airplanes by relativelysimple means, independent of whether such flight approach is effectedinadvertently or purposefully.

According to the invention, a method of the nature described in theheading of Claim No. 1 designed to solve the aforesaid task ischaracterized by the features listed in the identification of thisclaim, i.e.

-   -   a defendable ground object is assigned a virtual prohibited zone        spatially surrounding such object, with the outer boundary of        such zone providing for a sufficient horizontal minimum distance        and a vertical minimum distance determining a given minimum        crossing altitude from the ground object;    -   the prohibited zone is assigned a virtual correction zone        laterally surrounding it, the outer boundary of which provides        for a horizontal minimum distance from the outer boundary of the        prohibited zone in any case sufficient for forced deviation        corrections, and the altitude of which is equal to that of the        prohibited zone;    -   the correction zone is assigned a virtual alarm zone spatially        surrounding it, the outer boundary of which provides for both a        horizontal and vertical minimum distance from the outer boundary        of the correction zone in any case sufficient for manual        deviation corrections;    -   the geographical data of the outer boundary of at least the        alarm and the correction zone are recorded and digitally stored        together with the vertical minimum distance or the minimum        crossing altitude and stored in every airplane with        access-protection provided and displayed in the cockpit;    -   the momentary flight position is continuously recorded in a        satellite-based way and the momentary flight altitude        established and such instantaneous data are compared with the        geographical data of the outer boundaries of the alarm and the        correction zone;    -   in the event of an airplane's penetration into the alarm zone        detected by a position comparison of the aforesaid nature, a        warning signal is transmitted until the airplane leaves the        alarm zone, and the airplane is at the same time allowed to be        steered manually in order to make it leave the alarm zone;    -   in the event of an airplane's lateral penetration into the        correction zone detected by a position comparison of the        aforesaid nature, the airplane's manual steerability is, at        least until the airplane enters the alarm zone again, be        temporarily blocked and replaced by an autopilot control action        to the right or left forcing the airplane to leave the        correction zone;    -   in the event of an approach to the vertical minimum distance        determining the given minimum crossing altitude performed in        descent above the prohibited zone and the correction zone, a        descent limitation for the airplane to at minimum the minimum        crossing altitude is forced,

Such a method is decidedly safe and reliably prevents an airplane fromentering the prohibited zone. Whenever an airplane enters the alarm zoneby mistake, the crew receives a corresponding signal enabling it tomanually steer the airplane out of the alarm zone. In case this shouldbe impossible or purposefully prevented and the airplane should enterthe correction zone, the airplane's manual steerability will beinhibited with autopilot control being activated simultaneously untilthe airplane has left the correction zone.

This makes it impossible, for example in the case of terrorist attacks,to approach a ground object purposefully.

The development of Claim No. 2 ought to be sufficient for the majorityof safety purposes and is characterized by a particularly simple zonegeometry. However, it is in principle possible to chose another zonegeometry if this should be favorable considering the ground object to beprotected in the case at issue as well as the existing externalconditions.

By means of giving priority to anticollision control, the development ofClaim No. 3 prevents any collisions with other airplanes from occurringin the case of compulsory autopilot control action in the correctionzone.

According to Claim No. 4, a vector-oriented control program for theautopilot control system has proven particularly functional and simplein practice.

The development according to Claim No. 5 favors an always obtuse-angledflight correction by the autopilot control system, in order to achievethe most simple and safe avoidance maneuvers.

According to Claim No. 6, anticollision control should even besuperordinate to any descent limitation above the prohibited zone andthe correction zone in order to prevent collisions.

Claim No. 7 furthermore favors the enforcement of a given safetyaltitude by the autopilot control system within the correction zone inorder to prevent collisions with, for example, mountains and otherobstacles.

According to the invention, a facility appropriate to apply the inventedmethod for solving the aforesaid task of the nature described in theheading of Claim No. 8 is characterized by the features listed in theidentification of this claim, i.e.

-   -   the geographical data of the outer boundaries of the alarm zone        and the correction zone surrounding a central prohibited zone, a        vertical minimum distance determining an object-related minimum        crossing altitude as well as an environment-related safety        altitude are stored in the computer memory as safety variables;    -   the computer continuously compares the data from the        navigational system receiver and the altimeter with the safety        variables stored and, depending on the occurrence of particular        comparison results, starts the transmission of a warning signal        and/or compulsory control by the autopilot system with        subordinate priority of the anticollision system;    -   the display means in the cockpit are designed for optically        displaying the stored safety variables and the relative        momentary airplane position as well as any comparative values        resulting from this;    -   the computer including its memory as well as the navigational        system receiver are arranged in a control box provided with        access protection.

Such a facility is decidedly safe and relatively simple and, owing tothe access-protected arrangement of the control box in the airplane,cannot be manipulated without authorization. This makes it impossiblefor example for terrorists to impermissibly approach any protectedground objects after overwhelming the airplane's crew.

The preferential development of the facility according to Claim No, 9even increases safety by the fact that in the event of any unauthorizedintervention in the control box, an alarm is triggered or even anairplane's take-off prevented.

The other measures provided for in Claim No. 10 make sure that thecontrol box cannot be put out off operation by interrupting the externalpower supplies and that a radio set is activated in the case of anyunauthorized intervention.

The invention is explained in more detail below using illustratedexamples.

FIG. 1 shows an elementary diagram of a defendable ground objectsurrounded by several virtual zones of a particular altitude.

FIG. 2 shows an elementary diagram of a graphical cockpit display fromwhich the relative position relations of an airplane to a defendableground object may be gathered, whereas

FIG. 3 shows a simplified block diagram of a facility intended toprotect a ground object against airplanes impermissibly approaching it.

According to FIG. 1, a virtual prohibited zone 12 extends around adefendable ground object 10 such as a nuclear power station, which zonehas a circular section with a radius or horizontal minimum distance aand an altitude d equal to a given vertical minimum distance or aminimum crossing altitude in the case at issue. In order not to endangerthe ground object 10, no airplane is allowed to enter the prohibitedzone 12, i.e. penetrate into its outer boundary 14 from above or fromthe side.

The prohibited zone 12 is surrounded by a ring-shaped, virtualcorrection zone 16 concentric to it, which in the case at issue also hasa circular section, the same altitude d as the prohibited zone 12 and anouter boundary 18. The distance between the outer boundaries 18 and 14of the correction zone 16 and the prohibited zone 12 is equal to ahorizontal minimum distance b necessary to allow an airplane penetratinginto the correction zone 16 inadvertently or by intent to be safelyturned round to the outside by autopilot or forced control even inunfavorable flight situations without penetrating into the prohibitedzone 12.

The correction zone 16 is surrounded by a ring-shaped, virtual alarmzone 20 concentric to it, which in the case at issue also has a circularsection, the same altitude d as the prohibited zone 12 as well as thecorrection zone 16 and an outer boundary 22, The distance between theouter boundaries 22 and 18 of the alarm zone 20 and the correction zone16 is equal to a horizontal minimum distance c required to allow anairplane penetrating into the alarm zone 20 to be steered away from itto the outside by the airplane's crew without penetrating into thecorrection zone 16.

In the example at issue, a circular area is adjoining above theprohibited zone and the correction zone. The size of the verticalminimum distance c of this area may be equal to the horizontal minimumdistance c of the alarm zone 20. In the event of a descent in this area,such descent will be limited to at minimum the minimum crossing altituded by the autopilot system or by force.

The geographical conditions such as mountains 24 furthermore require aparticular minimum or safety altitude e, which in the correction zone 16is forced by an autopilot-controlled climb in the respective situations.

According to FIG. 2, the cockpit is equipped with a graphical display26, from which the relative position relations between the illustratedairplane 28 and the illustrated virtual prohibited, correction and alarmzones 12, 16, 20 may be gathered, A left avoidance beam 30 being tangentto the alarm zone 20 with an associated left avoidance angle 32 and aright avoidance beam 34 being tangent to the alarm zone 20 with anassociated right avoidance angle 36 result from the display. Theavoidance angles 32, 36 indicate the lateral flight deviation angles atminimum required in view of the momentary direction of the flight tomake the airplane 28 pass the alarm zone 20. In addition to theaforesaid, the display shows the momentary flight altitude 38, which is5,000 m in this example, and the momentary object distance 40 from thedefendable ground object 10, which is 250 km in this example. Theminimum crossing altitude d set for the defendable ground object 10 isadditionally shown.

Consequently, the airplane's crew is able to laterally circumnavigatethe virtual alarm zone 20 purposefully. In case the airplane 28 shouldnevertheless enter the alarm zone 20, which event would trigger thetransmission of a warning signal, the crew can still purposefully turnthe airplane 28 out of this zone to the outside. However, if theairplane enters the correction zone 16 inadvertently or purposefully,the autopilot will take over the steering of the airplane and by forcesteer the airplane laterally away from the correction zone 16 to thealarm zone 20. Only there, the crew may take over control of theairplane again. If the airplane is above the prohibited zone 12 and thecorrection zone 16 and the vertical minimum distance d determining thegiven minimum crossing altitude is approached in descent, the autopilotsystem forces the airplane's descent to be limited to at minimum theminimum crossing altitude.

According to FIG. 3, every airplane equipped this way will be providedwith an access-protected control box 42. This box contains amicrocomputer or computer 44 equipped with a memory and avector-oriented control program, a satellite-based GPS or navigationalsystem receiver 46 with an antenna 48, a computer interface 50 forconnecting devices as well as a safety device 52 equipped with anindependent power supply including a radio set. In addition to thealready mentioned graphical display 26, the cockpit of the airplaneincludes a TCAS or anticollision system 54, an autopilot system 56, analtimeter 58 as well as a both optical and acoustical alarm element 64responding in the alarm zone 20. All these devices are connected to thecomputer interface 50. The safety device 52 of the control box 42responds in the case of unauthorized intervention as well as in theevent that any outer or inner lines of the control box 42 should be cut.This activates the radio set which in turn for example triggers a radioreceiver 60 in the cockpit with an optical alarm element 62. In additionto the above, a non-illustrated function inhibition may be activated inorder to prevent an airplane from taking off in the event that thesafety device 52 responds.

The fixed geographical data of the outer boundaries 18 and 22 of thealarm zone 20 and the correction zone 16 as well as the vertical minimumdistance d determining the object-related minimum crossing altitude andthe environment-related safety altitude e and, if appropriate, furtherdata, are stored in the memory of the computer 44 of the control box 42as safety variables, These values are continuously compared with thedata from the navigational system receiver 46 and the altimeter 58.Subject to the occurrence of particular comparison results, thetransmission of an alarm signal and/or forced control by the autopilotsystem 56 with superordinate priority of the anticollision system 54are/is triggered.

Once all endangered and defendable ground objects 10 have this way beentaken into account by appropriately storing their geographical data, noairplane can penetrate into the prohibited zone 12 because theairplane's steerability will before be taken away from the pilot byforce. This will lead to a drastic increase of safety in particular inthe event of terrorist attacks.

1. Method for preventing airplanes from impermissibly approachingdefendable ground objects, with the momentary flight position beingrecorded in a satellite-based way and used for manual and automaticflight corrections, comprising the following features: a defendableground object is assigned a virtual prohibited zone spatiallysurrounding it, the outer boundary of which has a sufficient horizontalminimum distance from the ground object and a vertical minimum distancedetermining a given minimum crossing altitude; the prohibited zone isassigned a virtual correction zone laterally surrounding it, the outerboundary of which has a horizontal minimum distance from the outerboundary of the prohibited zone in any case sufficient for distancedeviation corrections and an altitude equal to that of the prohibitedzone; the correction zone is assigned a virtual alarm zone spatiallysurrounding it, the outer boundary of which has a horizontal minimumdistance from the outer boundary of the correction zone in any casesufficient for manual deviation corrections; the geographical data ofthe outer boundaries of at least the alarm and the correction zone arerecorded and, together with the vertical minimum distance or the minimumcrossing altitude, digitally stored and kept in every airplane withaccess protection provided as well as displayed in the cockpit; themomentary flight position is continuously recorded in a satellite-basedway and the momentary flight altitude established and such instantaneousdata are compared with the geographical data of the outer boundaries ofthe alarm zone and the correction zone; in the event of an airplane'spenetration into the alarm zone detected upon comparison of theaforesaid position data, a warning signal is transmitted until theairplane's withdrawal from the alarm zone, and the airplane is at thesame time allowed to be steered manually for the purposes of leaving thealarm zone; in the event of an airplane's lateral penetration into thecorrection zone detected upon comparison of the aforesaid position data,the airplane's manual steerability is temporarily inhibited and replacedby autopilot control to the right or left forcing withdrawal from thecorrection zone at least until the airplane reaches the alarm zoneagain; and in the event that the vertical minimum distance determiningthe given minimum crossing altitude is approached in descent above theprohibited zone and the correction zone, a descent limitation to atminimum the minimum crossing altitude is forced; and wherein theprohibited, correction and alarm zones each being defined by apredetermined radii.
 2. Method in accordance with claim No. 1, whereincircular prohibited, correction and alarm zones are used in thehorizontal section.
 3. Method in accordance with claim No. 1 or 2,wherein autopilot control within the correction zone is performed inconnection with superordinate anticollision control.
 4. Method inaccordance with claim 1 or 2, wherein autopilot control is triggered bya vector-oriented control program.
 5. Method in accordance with claim 1or 2, wherein autopilot control is subject to the angle of approach tothe correction zone, always performed in an obtuse angle to the right orleft.
 6. Method in accordance with claim 1 or 2, wherein the limitationof the airplane's descent above the prohibited zone and the correctionzone is effected in connection with superordinate anticollision control.7. Method in accordance with claim 1 or 2, whereinupon penetration intothe correction zone and in case the airplane is below a given safetyaltitude, for example a safety altitude determined by geographicconditions such as mountains, the autopilot control forces an optimalclimb until the safety altitude is reached.
 8. A facility for applyingthe method in accordance with claim 1 or 2, with a satellite-basednavigational system receiver, a computer provided with a memory, anautopilot system for airplanes, an anticollision system for airplanes,an altimeter and display and signaling means in the airplanc's cockpit,wherein: the geographical data of the outer boundaries of an alarm zoneand a correction zone surrounding a central prohibited zone, a verticalminimum distance determining an object-related minimum crossing altitudeand an environment-related safety altitude are stored in the memory ofthe computer as safety variables; the computer continuously compares thedata from the navigational system receiver and the altimeter with thestored safety variables and subject to this triggers the transmission ofa warning signal and/or forced autopilot control with superordinatepriority of the anticollision system upon occurrence of particularcomparison results; the display means in the cockpit are designed todisplay the stored safety variables and the relative momentary positionof the airplane as well as any resulting comparative values; and thecomputer with its memory and the navigational system receiver arearranged in an access-protected control box.
 9. A facility in accordancewith claim 8, wherein the control box is equipped with a safety deviceresponding in the case of any unauthorized intervention and designed totrigger a warning signal clement in the cockpit, and/or with a functioninhibition for take-off.
 10. A facility in accordance with claim 9,characterized by the fact that the safety device of the control box isequipped with an independent power supply in the control box and a radioset responding in the event of any unauthorized intervention andtriggering the safety function.
 11. A method for preventing airplanesfrom impermissibly approaching defendable ground objects, with themomentary flight position being recorded in a satellite-based way andused for manual and automatic flight corrections, comprising thefollowing features: a defendable pound object is assigned a virtualprohibited zone spatially surrounding it, the outer boundary of whichhas a sufficient horizontal minimum distance from the ground object anda vertical minimum distance determining a given minimum crossingaltitude; the prohibited zone is assigned a virtual correction zonelaterally surrounding it, the outer boundary of which has a horizontalminimum distance from the outer boundary of the prohibited zone in anyease sufficient for forced deviation corrections and an altitude equalto that of the prohibited zone; the correction zone is assigned avirtual alarm zone spatially surrounding it, the outer boundary of whichhas a horizontal minimum distance from the outer boundary of thecorrection zone in any case sufficient for manual deviation corrections;the geographical data of the outer boundaries of at least the alarm andthe correction zone are recorded and, together with the vertical minimumdistance or the minimum crossing altitude, digitally stored and kept inevery airplane with access protection provided as well as displayed inthe cockpit; the momentary flight position is continuously recorded in asatellite-based way and the momentary flight altitude established andsuch instantaneous data are compared with the geographical data of theouter boundaries of the alarm zone and the correction zone; in the eventof an airplane's penetration into the alarm zone detected uponcomparison of the aforesaid position data, a warning signal istransmitted until the airplane's withdrawal from the alarm zone, and theairplane is at the same time allowed to be steered manually for thepurposes of leaving the alarm zone; automatically replacing manualsteerability of an airplane with autopilot control if comparison of saidposition data indicates that said airplane laterally penetrates saidcorrection zone, said autopilot steering said airplane to the right orleft for forcing withdrawal from said correction zone, and automaticallyrestoring manual steerability of said airplane when said airplanereaches the alarm zone; and in the event that the vertical minimumdistance determining the given minimum crossing altitude is approachedin descent above the prohibited zone and the correction zone, a descentlimitation to at minimum the minimum crossing altitude is forced; andwherein the prohibited, correction and alarm zones each being defined bya respective predetermined radius.
 12. The method of claim 1, whereineach predetermined radius of said prohibited, correction and alarm zonesis a constant radius defining a respective cylindrically shaped zone.13. The method of claim 11, wherein each predetermined radius of saidprohibited, correction and alarm zones is a constant radius defining arespective cylindrically shaped zone.